Synthesis of glass ceramics from kaolin and dolomite mixture
来源期刊：International Journal of Minerals Metallurgy and Materials2017年第2期
论文作者：Fausto Rubio
文章页码：194 - 201
摘 要：Cordierite- and anorthite-based binary glass ceramics of the Ca O–Mg O–Al2O3–Si O2（CMAS） system were synthesized by mixing local and abundant raw minerals（kaolin and doloma by mass ratio of 82/18）. A kinetics study reveals that the activation energy of crystallization（E a） calculated by the methods of Kissinger and Marotta are 438 k J·mol-1 and 459 k J·mol-1,respectively. The Avrami parameter（n） is estimated to be approximately equal to 1,corresponding to the surface crystallization mechanism. X-ray diffraction（XRD） analysis shows that the anorthite and cordierite crystals are precipitated from the parent glass as major phases. Anorthite crystals first form at 850°C,whereas the μ-cordierite phase appears after heat treatment at 950°C. Thereafter,the cordierite allotropically transforms to α-cordierite at 1000°C. Complete densification is achieved at 950°C; however,the density slightly decreases at higher temperatures,reaching a stable value of 2.63 kg·m-3 between 1000°C and 1100°C. The highest Vickers hardness of 6 GPa is also obtained at 950°C. However,a substantial decrease in hardness is recorded at 1000°C; at higher sintering temperatures,it slightly increases with increasing temperature as the α-cordierite crystallizes.
Fausto Rubio2
2. Ceramics and Glass Institute,Consejo Superior de Investigaciones Cientificas
摘 要：Cordierite- and anorthite-based binary glass ceramics of the Ca O–Mg O–Al2O3–Si O2（CMAS） system were synthesized by mixing local and abundant raw minerals（kaolin and doloma by mass ratio of 82/18）. A kinetics study reveals that the activation energy of crystallization（E a） calculated by the methods of Kissinger and Marotta are 438 k J·mol-1 and 459 k J·mol-1,respectively. The Avrami parameter（n） is estimated to be approximately equal to 1,corresponding to the surface crystallization mechanism. X-ray diffraction（XRD） analysis shows that the anorthite and cordierite crystals are precipitated from the parent glass as major phases. Anorthite crystals first form at 850°C,whereas the μ-cordierite phase appears after heat treatment at 950°C. Thereafter,the cordierite allotropically transforms to α-cordierite at 1000°C. Complete densification is achieved at 950°C; however,the density slightly decreases at higher temperatures,reaching a stable value of 2.63 kg·m-3 between 1000°C and 1100°C. The highest Vickers hardness of 6 GPa is also obtained at 950°C. However,a substantial decrease in hardness is recorded at 1000°C; at higher sintering temperatures,it slightly increases with increasing temperature as the α-cordierite crystallizes.
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